Wind power technology has seen a substantial development over the recent years, especially that concerning three-bladed wind turbines. The largest state-of-the-art wind turbines have rotor diameters on the of 150 meters and generate approximately 6 MW of installed power. A problem with these large turbines is vibrations, due to i.a. supersonic tip speeds.
According to Betz' law, the maximum efficiency of a conventional wind turbine is 59.3%. In practice, the efficiency of today's wind power plants range between 35% and 40%. Several wind power plants are installed on the seabed in shallow waters, and floating plants are developed for use farther off shore. Conventional wind turbines generate considerable noise and pose severe threats to avian life.
Various types of floating wind power plants exist. The prior art includes WO 2014/112115 A1, which describes a floating wind-power generation plant, where a wind-power generator is installed on top of a floating body moored at a mooring position by a mooring line and electric power generated by the wind-power generator is supplied to a cable. The prior art also included WO 2010/019050 A1, which describes a foundation for an offshore wind turbine generator. The foundation is a self-floating and stable construction of reinforced concrete, comprising a foundation structure, a hollow, substantially conical tower structure arranged on the foundation structure and having a lower external diameter less than the smallest transversal dimension of the foundation structure, since the diameter of the tower structure gradually decreases upwards toward the upper portion of the tower structure. The prior art also includes WO 99/02856 A1, which describes an installation comprising windmills mounted in a frame. The frame is provided with float bodies, and it is capable of rotation about a vertical axis in order to turn the windmills towards the wind. In order to keep the windmills upright, supporting means, for example a body which is anchored to the bottom, are disposed some distance away from the plane of the windmills.
Prior art wind power plants, with conventional, pylon-mounted generators, have limited performance characteristics in high winds; they are maintenance intensive and must be closed down completely when repairs or refurbishments become necessary. It is therefore a need for a wind power plant which is easier to operate and maintain, and can handle high wind loads.
The prior art also includes GB 2461772 A, describing a floating wind power generation apparatus comprising a floating platform, a frame and plurality of wind power generators arranged in the frame. The wind power generators are individually mounted to the frame via upper and lower trunnion shafts to allow the individual generators to align with the wind. During assembly, the wind power generators are first mounted on the frame, before the frame is installed on the floating platform, or vice versa. A generator unit is connected to each wind-wheel. The position of the floating platform is fixed by means of an anchor.
The invention is an improvement of the prior art and offers in addition other advantages.